A person who dosn't follow the normal process of sex and goes by his own rules and regulations, and usually acts like a crazed sex monster either in the bedroom or the vast urine smelling vicinity of the disabled toilets within a nursing home.

Frodo - "Cor blimey! Gandalf acted like a real sex maverick last night"
Batman - "Really! i bet he filled your hole to the brim, the way he uses that stick of his, it makes me wonder how it didnt hurt you"